FISHERY BULLETIN: VOL. 87. NO. 3, 1989 



depths between 51 and 75 m, decrease to a low at 

 151-200 m, and then increase again at depths 

 >400 m. The increase in catch per tow at the 

 deep water stations is due to the dominance of 

 two mesopelagic lantern fishes, Ceratoscopelus 

 maderensis and Benthosema glaciate, which 

 account for 47% of all larvae at these depths. 

 Night catches exceeded day and twilight catches 

 except between 101 and 400 m. At these water 

 column depths the dominant taxa are Sebastes 

 spp.; silver hake, Merluccius bilinearis; offshore 

 hake, Merluccius alhidus; Gulf Stream flounder, 

 Citharichthys arctifrons; Urophycis spp.; At- 

 lantic herring, Clupea harengus; and 



Ammodytes spp., all of which comprise 71% of 

 the total catch. The twilight catch at column 

 depths between 101 and 150 m exceeds both the 

 night and day catches and reflects the high twi- 

 light catches for Gulf Stream flounder, offshore 

 hake, and to some extent butterfish, Peprilus 

 triacanthus. 



The daily cycle in mean catch per 10 m^ for all 

 larvae is shown in Figure 3a. Catches were high- 

 est between hour intervals 1 and 6, with max- 

 imum catches at hour 2. Minimum catches oc- 

 curred between intervals 10 and 17 and averaged 

 only 39%> of the catch at interval 2. The ratios of 

 the catch at each hour interval, divided by the 



450 

 400 

 350 



300 



°250 



X 



u 



200 

 150 

 100 

 50 







0.2 



* * 



10 12 M 16 18 20 22 

 TIME INTERVAL 



Figure 3. — Mean catch per 10 m~ by time interval.s and standard error bars and 

 plot of ratios of catch at time interval 2 with the fitted curves. 



422 



